The subject matter disclosed herein relates to hydrogen-cooled electric generators and, more particularly, to a system for controlling hydrogen flow and purity in a hydrogen-cooled electric generator.
Some power plant systems, for example certain nuclear, simple cycle and combined cycle power plant systems, employ hydrogen as a coolant for generators, which, during operation, produce large amounts of heat. Hydrogen's high heat capacity, low density and ability to reduce windage losses improves the output of the electric generator and the efficiency of the overall system. These properties make it desirable to maintain a high level of hydrogen purity within the generator. However, maintaining purity of the hydrogen in these generators is typically costly. Some power plant systems remove hydrogen via a scavenging system that extracts a portion of a mixture of gases from within the generator or drain enlargements, vents the portion of a mixture of gases to the ambient and replaces it with clean hydrogen. These systems employ a set of manually adjusted needle valves that regulate the flow of gases through the scavenging system. These manually adjusted needle valves fail to precisely control the flow of hydrogen out of the generator which may cause the generator to run inefficiently.